JP4572227B2 - Magnetostrictive torque sensor and electric steering device - Google Patents

Magnetostrictive torque sensor and electric steering device Download PDF

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JP4572227B2
JP4572227B2 JP2007308817A JP2007308817A JP4572227B2 JP 4572227 B2 JP4572227 B2 JP 4572227B2 JP 2007308817 A JP2007308817 A JP 2007308817A JP 2007308817 A JP2007308817 A JP 2007308817A JP 4572227 B2 JP4572227 B2 JP 4572227B2
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torque
detection
magnetostrictive
torque sensor
bias
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JP2009133673A (en
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吉裕 大庭
尚 三好
浩壱 藤田
篤彦 米田
康夫 清水
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Honda Motor Co Ltd
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Honda Motor Co Ltd
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Priority to US12/324,024 priority patent/US7938026B2/en
Priority to EP08020640A priority patent/EP2065691B1/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L3/00—Measuring torque, work, mechanical power, or mechanical efficiency, in general
    • G01L3/02—Rotary-transmission dynamometers
    • G01L3/04—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft
    • G01L3/10—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating
    • G01L3/101—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating involving magnetic or electromagnetic means
    • G01L3/102—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating involving magnetic or electromagnetic means involving magnetostrictive means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0457—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such
    • B62D5/046—Controlling the motor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0457—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such
    • B62D5/0481—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such monitoring the steering system, e.g. failures
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0457—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such
    • B62D5/0481—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such monitoring the steering system, e.g. failures
    • B62D5/049—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such monitoring the steering system, e.g. failures detecting sensor failures
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits
    • B62D6/08—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits responsive only to driver input torque
    • B62D6/10—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits responsive only to driver input torque characterised by means for sensing or determining torque
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L3/00—Measuring torque, work, mechanical power, or mechanical efficiency, in general
    • G01L3/02—Rotary-transmission dynamometers
    • G01L3/04—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft
    • G01L3/10—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating
    • G01L3/101—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating involving magnetic or electromagnetic means
    • G01L3/105—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating involving magnetic or electromagnetic means involving inductive means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
    • G01L5/22—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring the force applied to control members, e.g. control members of vehicles, triggers
    • G01L5/221—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring the force applied to control members, e.g. control members of vehicles, triggers to steering wheels, e.g. for power assisted steering

Description

この発明は、磁歪に起因する磁気特性の変化に基づいてトルクを検出する磁歪式トルクセンサと、これを備えた電動ステアリング装置に関するものである。   The present invention relates to a magnetostrictive torque sensor that detects torque based on a change in magnetic characteristics caused by magnetostriction, and an electric steering device including the magnetostrictive torque sensor.

従来から、磁気異方性を備えた磁歪膜を回転軸に設けて、検出コイルで回転軸へのトルク入力に応じた磁歪膜の透磁率の変化を検出する磁歪式のトルクセンサが知られている（例えば、特許文献１参照）。
例えば、この磁歪式のトルクセンサには、図６に示すようなものがある。この図６に示す磁歪式のトルクセンサ１３０は、自動車等のステアリング装置の回転軸に作用するトルクを検出ものであり、磁気異方性を備え磁化容易な方向を異にする２つの磁歪膜１３１，１３２を回転軸１０５の周面に備えている。さらに、これら磁歪膜１３１，１３２から所定の隙間をもって対向する位置に、それぞれ検出コイル１３３，１３４を備え、これら検出コイル１３３，１３４のインダクタンス変化が、互いに逆相となる電圧信号ＶＴ１，ＶＴ２として信号変換部１３８，１３９よりそれぞれ出力され、さらに、電圧信号ＶＴ１，ＶＴ２を差動増幅した電圧信号がトルク検出信号ＶＴ３として差動増幅部１４０より出力される。 Conventionally, there has been known a magnetostrictive torque sensor in which a magnetostrictive film having magnetic anisotropy is provided on a rotating shaft, and a change in permeability of the magnetostrictive film according to torque input to the rotating shaft is detected by a detection coil. (For example, refer to Patent Document 1).
For example, there is a magnetostrictive torque sensor as shown in FIG. The magnetostrictive torque sensor 130 shown in FIG. 6 detects torque acting on the rotating shaft of a steering device such as an automobile, and has two magnetostrictive films 131 having magnetic anisotropy and different directions of easy magnetization. , 132 are provided on the peripheral surface of the rotating shaft 105. Further, detection coils 133 and 134 are provided at positions facing these magnetostrictive films 131 and 132 with a predetermined gap, respectively, and the inductance changes of these detection coils 133 and 134 are signaled as voltage signals VT1 and VT2 that are opposite to each other. A voltage signal obtained by differentially amplifying the voltage signals VT1 and VT2 is output from the differential amplifier 140 as a torque detection signal VT3.

ところで、上述の磁歪式トルクセンサにあっては、シャフトへの外部磁界の影響で、検出信号である電圧信号ＶＴ１，ＶＴ２が変動してしまい、その結果、トルク検出信号ＶＴ３が変動してしまう場合がある。そのため、近年、検出コイルに励磁電流を流して回転軸を磁化させることで外部磁気タフネスを向上させるものが提案されている。   By the way, in the magnetostrictive torque sensor described above, the voltage signals VT1 and VT2 that are detection signals fluctuate due to the influence of the external magnetic field on the shaft, and as a result, the torque detection signal VT3 fluctuates. There is. For this reason, in recent years, there has been proposed one that improves the external magnetic toughness by flowing an excitation current through the detection coil to magnetize the rotating shaft.

この磁歪式トルクセンサの外部磁気タフネスを向上するための構成の一例を図７に示す。なお、検出コイル１３３と検出コイル１３４とは、同様の回路が並列接続されるだけであるため、図７では、これらの並列部分を一つの回路構成として模式的に示している。
図７に示す回路構成は、上述した検出コイル１３３，１３４にコンデンサＣを介してトルク検出用の交流電流を通電する交流回路１１１と、この交流回路１１１と並列に接続されシャフト磁化用の直流分を通電する直流回路１１２と、さらに、検出コイル１３３，１３４とアースＥとの間に介装された電流制限抵抗１１３とを備え、交流回路１１１及び直流回路１１２によって検出コイル１３３，１３４に同時に通電を行い、検出コイル１３３，１３４と電流制限抵抗１１３との間の電圧信号を信号変換部１３８，１３９に入力するように構成されている。
特開２００６−６４４４５号公報 An example of a configuration for improving the external magnetic toughness of this magnetostrictive torque sensor is shown in FIG. Note that the detection coil 133 and the detection coil 134 are simply connected in parallel with each other, and in FIG. 7, these parallel portions are schematically shown as one circuit configuration.
The circuit configuration shown in FIG. 7 includes an AC circuit 111 for passing an AC current for torque detection through the capacitor C to the detection coils 133 and 134 described above, and a DC component for shaft magnetization connected in parallel with the AC circuit 111. And a current limiting resistor 113 interposed between the detection coils 133 and 134 and the earth E, and the detection coils 133 and 134 are simultaneously energized by the AC circuit 111 and the DC circuit 112. The voltage signal between the detection coils 133 and 134 and the current limiting resistor 113 is input to the signal conversion units 138 and 139.
JP 2006-64445 A

しかしながら、上述の図７に示す磁歪式トルクセンサにあっては、シャフトを磁化させるために、比較的大きな電流を検出コイルに通電し続ける構成になっているため、消費電流が増加してしまう。
また、直流回路による通電によりトルク検出や磁歪式トルクセンサの故障検出に影響を及ぼす虞がある。 However, since the magnetostrictive torque sensor shown in FIG. 7 is configured to keep a relatively large current supplied to the detection coil in order to magnetize the shaft, the current consumption increases.
Further, energization by the DC circuit may affect torque detection and failure detection of the magnetostrictive torque sensor.

そこで、この発明は、信頼性を向上しつつ消費電流を低減することができる磁歪式トルクセンサ及び電動ステアリング装置を提供するものである。   Accordingly, the present invention provides a magnetostrictive torque sensor and an electric steering device that can reduce current consumption while improving reliability.

上記の課題を解決するために、請求項１に記載した磁歪式トルクセンサは、強磁性のシャフト（例えば、実施の形態におけるピニオン軸５）に設けられた磁歪膜（例えば、実施の形態における第１磁歪膜３１，第２磁歪膜３２）と、該磁歪膜の磁気特性の変化を検出し、該検出結果に基づいて前記シャフトに入力されるトルクを検出するトルク検出手段と、前記シャフトにバイアス磁界を印加して磁化させるバイアス磁化手段（例えば、実施の形態における励磁信号発生部４１、スイッチ手段４２、第１検出コイル３３および第２検出コイル３４で構成される）とを備え、該バイアス磁化手段が所定のタイミングで一時的にシャフトを十分に磁化させるために予め設定された所定時間だけバイアス磁界を発生させる磁歪式トルクセンサであって、前記バイアス磁化手段は、前記シャフトに対向して設けられたコイルに電流を流すことによりバイアス磁界を発生させることを特徴とする。 In order to solve the above-described problem, a magnetostrictive torque sensor according to a first aspect of the present invention includes a magnetostrictive film (for example, a first magnetostrictive film in the embodiment) provided on a ferromagnetic shaft (for example, the pinion shaft 5 in the embodiment). A first magnetostrictive film 31, a second magnetostrictive film 32), a torque detecting means for detecting a change in magnetic characteristics of the magnetostrictive film, and detecting a torque input to the shaft based on the detection result; and a bias applied to the shaft Bias magnetizing means for applying and magnetizing a magnetic field (for example, comprised of the excitation signal generating unit 41, the switch means 42, the first detection coil 33 and the second detection coil 34 in the embodiment), and the bias magnetization It means a magnetostrictive torque sensor that generates only the bias magnetic field a preset time to fully magnetized temporarily shaft at a predetermined timing , The bias magnetization device is characterized in that Ru is generated a bias magnetic field by passing a current through the coil provided to face the shaft.

請求項２に記載した磁歪式トルクセンサは、請求項１に記載の磁歪式トルクセンサにおいて、前記バイアス磁化手段が、起動時に一時的にバイアス磁界を発生させることを特徴とする。   A magnetostrictive torque sensor according to a second aspect is the magnetostrictive torque sensor according to the first aspect, wherein the bias magnetization means temporarily generates a bias magnetic field at the time of activation.

請求項３に記載した磁歪式トルクセンサは、請求項１又は２に記載の磁歪式トルクセンサにおいて、前記検出手段の検出結果に基づいて故障検出を行う故障検出手段（例えば、実施の形態における故障検出部５４）を備え、前記バイアス磁化手段が所定のタイミングで一時的にバイアス磁界を発生させている間は、トルクの検出及び故障検出を禁止することを特徴とする。   The magnetostrictive torque sensor according to claim 3 is the magnetostrictive torque sensor according to claim 1 or 2, wherein the magnetostrictive torque sensor detects a failure based on a detection result of the detection unit (for example, a failure in the embodiment). A detection unit 54), and while the bias magnetization means temporarily generates a bias magnetic field at a predetermined timing, detection of torque and failure detection are prohibited.

請求項４に記載した磁歪式トルクセンサは、請求項１に記載の磁歪式トルクセンサにおいて、前記トルク検出手段は、前記磁歪膜の磁気特性の変化を検出するために前記シャフトに対向して設けられた検出コイルに電流を流すことによりトルクを検出し、前記バイアス磁化手段は、前記トルク検出手段がトルク検出時に前記検出コイルに電流を通電する時間よりも長い時間前記検出コイルに電流を流すことによりバイアス磁界を発生させることを特徴とする。
請求項５に記載した磁歪式トルクセンサは、請求項１に記載の磁歪式トルクセンサにおいて、前記トルク検出手段は、前記バイアス磁化手段によって一時的にバイアス磁界を発生させている間は、トルクの検出を禁止することを特徴とする。
請求項６に記載した磁歪式トルクセンサは、請求項１に記載の磁歪式トルクセンサにおいて、前記トルク検出手段は、前記磁歪膜の磁気特性の変化を検出するために前記シャフトに対向して設けられた検出コイルに電流をＰＷＭ制御にて通電することによりトルクを検出し、前記バイアス磁化手段が、前記シャフトにバイアス磁界を印加するために前記検出コイルに流す電流をＰＷＭ制御にて行い、前記バイアス磁化手段のＰＷＭ制御のＯＮ時間が前記トルク検出手段のＰＷＭ制御のＯＮ時間よりも長いことを特徴とする。
請求項７に記載した電動ステアリング装置は、操舵トルクを磁歪式トルクセンサによって検出し、検出した操舵トルクに応じて電動機を駆動して車両を転舵させる電動ステアリング装置において、前記磁歪式トルクセンサが、請求項１乃至６の何れか一項に記載の磁歪式トルクセンサであることを特徴とする。 The magnetostrictive torque sensor according to claim 4 is the magnetostrictive torque sensor according to claim 1, wherein the torque detecting means is provided to face the shaft in order to detect a change in magnetic characteristics of the magnetostrictive film. Torque is detected by passing a current through the detected coil , and the bias magnetizing means causes the current to flow through the detection coil for a time longer than a time during which the torque detecting means energizes the detection coil during torque detection. To generate a bias magnetic field.
The magnetostrictive torque sensor according to claim 5 is the magnetostrictive torque sensor according to claim 1, wherein the torque detecting means generates torque while the bias magnetic means temporarily generates a bias magnetic field. It is characterized by prohibiting detection.
The magnetostrictive torque sensor according to claim 6 is the magnetostrictive torque sensor according to claim 1, wherein the torque detecting means is provided to face the shaft in order to detect a change in magnetic characteristics of the magnetostrictive film. detecting a torque current in the detection coil that is by energizing at PWM control, the bias magnetization means, have rows in PWM control the current flowing in the detection coil in order to apply a bias magnetic field to the shaft, The ON time of PWM control of the bias magnetizing means is longer than the ON time of PWM control of the torque detecting means.
According to a seventh aspect of the present invention, there is provided an electric steering apparatus in which a steering torque is detected by a magnetostrictive torque sensor, and the motor is steered by driving an electric motor according to the detected steering torque. A magnetostrictive torque sensor according to any one of claims 1 to 6.

請求項１に記載した発明によれば、バイアス磁化手段によって所定のタイミングで一時的にシャフトにバイアス磁界をかけてバイアス磁化させることで、バイアス磁界をかけ終えた後も、強磁性のシャフトに磁化が残留してバイアス磁化として作用させることができるため、外部磁気タフネスの向上を図りつつ、従来のように常時電流を通電している場合と比較して、通電を一時的に行う分だけ消費電流を低減することができるとともに、例えばトルク検出や故障検出などへの影響も低減して信頼性を向上することができる効果がある。
また、消費電流が低減されることで回路の発熱を抑制できるため、耐熱性の比較的低い部品を使用することが可能になり、したがって、部品のコスト低減を図ることができる。 According to the first aspect of the present invention, even after the application of the bias magnetic field is completed, the magnetization is applied to the ferromagnetic shaft by temporarily applying the bias magnetic field to the shaft at a predetermined timing by the bias magnetization means. As a result, it is possible to act as bias magnetization, so that the external magnetic toughness is improved, and compared to the case where current is always energized as in the prior art, the current consumption is equivalent to the amount that is temporarily energized. In addition, there is an effect that reliability can be improved by reducing influence on torque detection, failure detection, and the like.
In addition, since the heat generation of the circuit can be suppressed by reducing the current consumption, it is possible to use a component having relatively low heat resistance, and thus it is possible to reduce the cost of the component.

請求項２に記載した発明によれば、請求項１の効果に加え、磁歪式トルクセンサを起動する時にバイアス磁界を一時的に発生させることで、バイアス磁界によるトルク検出への影響を抑制することができるため、外部磁界タフネスを向上しつつトルク検出の信頼性を向上できる効果がある。   According to the second aspect of the present invention, in addition to the effect of the first aspect, the bias magnetic field is temporarily generated when starting the magnetostrictive torque sensor, thereby suppressing the influence of the bias magnetic field on the torque detection. Therefore, it is possible to improve the reliability of torque detection while improving the external magnetic field toughness.

請求項３に記載した発明によれば、請求項１又は２の効果に加え、故障検出手段によって故障検出を行っているときにはバイアス磁界が発生していないため、バイアス磁界が故障検出へ影響を及ぼすのを防止することができ、したがって、外部磁界タフネスを向上しつつ故障検出手段による故障検出の信頼性を向上できる効果がある。   According to the third aspect of the invention, in addition to the effect of the first or second aspect, since no bias magnetic field is generated when failure detection is performed by the failure detection means, the bias magnetic field affects failure detection. Therefore, it is possible to improve the reliability of failure detection by the failure detection means while improving the external magnetic field toughness.

請求項４に記載した発明によれば、請求項１乃至３の何れか一項の効果に加え、電動ステアリング装置の操舵トルクを検出するための磁歪式トルクセンサの外部磁界タフネスを向上しつつ消費電流を低減することができるため、電動ステアリング装置の消費電流低減及び信頼性の向上に寄与することができる効果がある。   According to the invention described in claim 4, in addition to the effect of any one of claims 1 to 3, consumption is improved while improving the external magnetic field toughness of the magnetostrictive torque sensor for detecting the steering torque of the electric steering device. Since the current can be reduced, there is an effect that the current consumption of the electric steering device can be reduced and the reliability can be improved.

次に、この発明に係る磁歪式トルクセンサおよびこれを備えた車両用の電動パワーステアリング装置の第１の実施形態を、図面を参照して説明する。
図１に示すように、車両用電動パワーステアリング装置（電動ステアリング装置）１００はハンドル（操舵手段）２に連結されたステアリングシャフト１を備えている。ステアリングシャフト１は、ハンドル２に一体結合されたメインステアリングシャフト３と、ラック＆ピニオン機構のピニオン７が設けられたピニオン軸５とが、ユニバーサルジョイント４によって連結されて構成されている。なお、ピニオン軸５は、強磁性体である例えば鉄などで形成されている。 Next, a first embodiment of a magnetostrictive torque sensor according to the present invention and an electric power steering apparatus for a vehicle including the same will be described with reference to the drawings.
As shown in FIG. 1, a vehicle electric power steering device (electric steering device) 100 includes a steering shaft 1 connected to a handle (steering means) 2. The steering shaft 1 is constituted by connecting a main steering shaft 3 integrally coupled to a handle 2 and a pinion shaft 5 provided with a pinion 7 of a rack and pinion mechanism by a universal joint 4. The pinion shaft 5 is formed of a ferromagnetic material such as iron.

ピニオン軸５はその下部、中間部、上部を軸受６ａ，６ｂ，６ｃによって支持されており、ピニオン７はピニオン軸５の下端部に設けられている。ピニオン７は、車幅方向に往復動し得るラック軸８のラック歯８ａに噛合し、ラック軸８の両端には、タイロッド９，９を介して転舵輪としての左右の前輪１０，１０が連結されている。この構成により、ハンドル２の操舵時に通常のラック＆ピニオン式の転舵操作が可能であり、前輪１０，１０を転舵させて車両の向きを変えることができる。ここで、ラック軸８、ラック８ａ、タイロッド９は転舵機構を構成する。   The lower part, the middle part, and the upper part of the pinion shaft 5 are supported by bearings 6 a, 6 b and 6 c, and the pinion 7 is provided at the lower end part of the pinion shaft 5. The pinion 7 meshes with the rack teeth 8a of the rack shaft 8 that can reciprocate in the vehicle width direction, and left and right front wheels 10, 10 as steered wheels are connected to both ends of the rack shaft 8 via tie rods 9, 9. Has been. With this configuration, a normal rack and pinion type steering operation can be performed when the steering wheel 2 is steered, and the front wheels 10 and 10 can be steered to change the direction of the vehicle. Here, the rack shaft 8, the rack 8a, and the tie rod 9 constitute a steering mechanism.

また、電動パワーステアリング装置１００は、ハンドル２による操舵力を軽減するための補助操舵力を供給する電動機１１を備えており、この電動機１１の出力軸に設けられたウォームギヤ１２が、ピニオン軸５において中間部の軸受６ｂの下側に設けられたウォームホイールギヤ１３に噛合している。また、ピニオン軸５において中間部の軸受６ｂと上部の軸受６ｃとの間には、磁歪に起因する磁気特性の変化に基づいてトルクを検出する磁歪式トルクセンサ３０が配置されている。   The electric power steering apparatus 100 includes an electric motor 11 that supplies an auxiliary steering force for reducing the steering force by the handle 2, and a worm gear 12 provided on the output shaft of the electric motor 11 is connected to the pinion shaft 5. It meshes with a worm wheel gear 13 provided below the intermediate bearing 6b. In the pinion shaft 5, a magnetostrictive torque sensor 30 that detects torque based on a change in magnetic characteristics caused by magnetostriction is disposed between the intermediate bearing 6b and the upper bearing 6c.

図２に示すように、磁歪式トルクセンサ３０は、ピニオン軸５の外周面に周方向全周に亘って環状に設けられた第１磁歪膜３１と第２磁歪膜３２とを備え、これら第１磁歪膜３１と第２磁歪膜３２とがピニオン軸５の軸線方向に沿って並んで配置されている。第１磁歪膜３１および第２磁歪膜３２は、歪みに対して透磁率の変化が大きい素材からなる金属膜であり、ピニオン軸５の外周に、例えば、メッキ法等で形成したＮｉ−Ｆｅ系の合金膜からなる。   As shown in FIG. 2, the magnetostrictive torque sensor 30 includes a first magnetostrictive film 31 and a second magnetostrictive film 32 that are annularly provided on the outer peripheral surface of the pinion shaft 5 over the entire circumference. The first magnetostrictive film 31 and the second magnetostrictive film 32 are arranged side by side along the axial direction of the pinion shaft 5. The first magnetostrictive film 31 and the second magnetostrictive film 32 are metal films made of a material having a large change in permeability with respect to strain, and are formed on the outer periphery of the pinion shaft 5 by, for example, a Ni—Fe system. It consists of an alloy film.

第１磁歪膜３１は、磁気異方性を備えておりピニオン軸５の軸線に対して約４５度傾斜した方向にその磁化容易な方向（図２中、矢印で示す方向）が設定されている。第２磁歪膜３２も、第１磁歪膜３１と同様に磁気異方性を備えており、その磁化容易な方向（図２中、矢印で示す）が第１磁歪膜３１の磁化容易な方向に対して９０度の方向に設定されている。   The first magnetostrictive film 31 has magnetic anisotropy, and its easy magnetization direction (direction indicated by an arrow in FIG. 2) is set in a direction inclined about 45 degrees with respect to the axis of the pinion shaft 5. . Similarly to the first magnetostrictive film 31, the second magnetostrictive film 32 also has magnetic anisotropy, and the direction of easy magnetization (indicated by an arrow in FIG. 2) is the direction of easy magnetization of the first magnetostrictive film 31. The direction is set to 90 degrees.

第１磁歪膜３１および第２磁歪膜３２は、それぞれの磁化容易な方向に沿って圧縮力および引っ張り力が作用すると、この圧縮力および引っ張り力に応じて透磁率が大きく増減するようになっており、ピニオン軸５に右又は左回転のトルクが作用すると、第１磁歪膜３１と第２磁歪膜３２とのいずれか一方に磁化容易な方向に沿う圧縮力が作用し、第１磁歪膜３１と第２磁歪膜３２とのいずれか他方に磁化容易な方向に沿う引っ張り力が作用することとなる。これにより、第１磁歪膜３１と第２磁歪膜３２とのいずれか一方の透磁率が増加し、第１磁歪膜３１と第２磁歪膜３２とのいずれか他方の透磁率が減少する。   The first magnetostrictive film 31 and the second magnetostrictive film 32 have their permeability greatly increased or decreased according to the compressive force and the tensile force when a compressive force and a tensile force are applied along the respective easy magnetization directions. When a torque of right or left rotation acts on the pinion shaft 5, a compressive force along the direction of easy magnetization acts on either the first magnetostrictive film 31 or the second magnetostrictive film 32, and the first magnetostrictive film 31. And the second magnetostrictive film 32 are subjected to a tensile force along the direction of easy magnetization. As a result, the magnetic permeability of one of the first magnetostrictive film 31 and the second magnetostrictive film 32 increases, and the magnetic permeability of the other of the first magnetostrictive film 31 and the second magnetostrictive film 32 decreases.

第１磁歪膜３１には、所定の隙間を有した状態で第１検出コイル３３が対向配置され、同様に、第２磁歪膜３２には、所定の隙間を有した状態で第２検出コイル３４が対向配置されている。
第１、第２検出コイル３３，３４は、上述した第１磁歪膜３１及び第２磁歪膜３２の透磁率の変化を検出するものであり、第１磁歪膜３１の透磁率が変化すると、第１検出コイル３３のインダクタンスが増加又は減少し、第２磁歪膜３２の透磁率が変化すると、第２検出コイル３４のインダクタンスが増加又は減少することとなる。 A first detection coil 33 is disposed opposite to the first magnetostrictive film 31 with a predetermined gap. Similarly, the second detection coil 34 has a predetermined gap on the second magnetostrictive film 32. Are arranged opposite to each other.
The first and second detection coils 33 and 34 detect changes in the magnetic permeability of the first magnetostrictive film 31 and the second magnetostrictive film 32 described above. When the magnetic permeability of the first magnetostrictive film 31 changes, When the inductance of the first detection coil 33 increases or decreases and the magnetic permeability of the second magnetostrictive film 32 changes, the inductance of the second detection coil 34 increases or decreases.

第１検出コイル３３および第２検出コイル３４は、それぞれ検出回路３５に接続されている。この検出回路３５は、図示しない車載バッテリーから電源供給がなされており、第１検出コイル３３および第２検出コイル３４のインダクタンス変化をトルク入力に対して互いに逆相の、電源の正側の電圧（例えば、５Ｖ）を上限値とするとともに電源の負側の電圧（例えば、アース電位である０Ｖ）を下限値とする電圧信号ＶＴ１，ＶＴ２に変換する変換回路３８，３９を備え、この変換された電圧信号ＶＴ１，ＶＴ２をそれぞれ電子制御装置５０に向けて出力する。
また、検出回路３５は、電圧信号ＶＴ１，ＶＴ２を差動増幅する差動増幅回路４０を有し、この差動増幅回路４０から出力される差動増幅信号であるトルク検出信号ＶＴ３を電子制御装置５０に出力する（図１参照）。なお、トルク検出信号ＶＴ３も上述した電圧信号ＶＴ１，ＶＴ２と同様に差動増幅回路４０の電源電圧内で変動する電圧信号となる。 The first detection coil 33 and the second detection coil 34 are each connected to a detection circuit 35. The detection circuit 35 is supplied with power from an in-vehicle battery (not shown), and the inductance change of the first detection coil 33 and the second detection coil 34 is opposite in phase to the torque input, and the positive voltage of the power supply ( For example, conversion circuits 38 and 39 are provided for converting voltage signals VT1 and VT2 having an upper limit value of 5V) and a negative voltage of the power source (for example, 0V being the ground potential) as a lower limit value. The voltage signals VT1 and VT2 are output to the electronic control unit 50, respectively.
Further, the detection circuit 35 includes a differential amplifier circuit 40 that differentially amplifies the voltage signals VT1 and VT2, and an electronic control device receives a torque detection signal VT3 that is a differential amplification signal output from the differential amplifier circuit 40. 50 (see FIG. 1). The torque detection signal VT3 is also a voltage signal that fluctuates within the power supply voltage of the differential amplifier circuit 40, similarly to the voltage signals VT1 and VT2 described above.

検出回路３５には、さらに第１検出コイル３３及び第２検出コイルに励磁電流を流すための電源（図中、Ｖｃｃで示す）が制限抵抗３６，３７を介してそれぞれ第１検出コイル３３と変換回路３８との間、および、第２検出コイル３４と変換回路３９との間に合流接続されている。さらに、第１検出コイル３３及び第２検出コイルとアースとの間にはバイポーラトランジスタなどのスイッチ手段４２が設けられ、このスイッチ手段４２は、励磁信号発生部４１が接続されており、この励磁信号発生部４１から出力される励磁信号に基づいてスイッチング動作を行う。   In the detection circuit 35, a power source (indicated by Vcc in the figure) for flowing an exciting current to the first detection coil 33 and the second detection coil is converted into the first detection coil 33 via the limiting resistors 36 and 37, respectively. A junction connection is made between the circuit 38 and between the second detection coil 34 and the conversion circuit 39. Further, a switch means 42 such as a bipolar transistor is provided between the first detection coil 33 and the second detection coil and the ground. The switch means 42 is connected to an excitation signal generator 41. A switching operation is performed based on the excitation signal output from the generator 41.

励磁信号発生部４１は、電子制御装置５０に接続されており、所定のタイミングである車両のイグニッションがＯＮ操作された直後の磁歪式トルクセンサ３０の起動時に、一時的にピニオン軸５を磁化させるためのＰＷＭ制御（以下、単に軸磁化ＰＷＭ制御と称す）が行われるように設定されている。励磁信号発生部４１は、さらにピニオン軸５を磁化させるための軸磁化ＰＷＭ制御を行っていないとき、つまり磁歪式トルクセンサ３０の通常動作時に、第１磁歪膜３１及び第２磁歪膜３２による透磁率変化を検出するためのＰＷＭ制御（以下、単にトルク検出ＰＷＭ制御と称す）を行うように設定されている。ここで、上述した「一時的」とは、ピニオン軸５を十分に磁化させるために予め設定された所定時間だけ軸磁化ＰＷＭ制御を行い、その後、この軸磁化ＰＷＭ制御を停止することを意味している。なお、軸磁化ＰＷＭ制御を行う所定時間は、ピニオン軸５の磁気特性に応じて適宜設定すればよい。   The excitation signal generator 41 is connected to the electronic control unit 50, and temporarily magnetizes the pinion shaft 5 when the magnetostrictive torque sensor 30 is started immediately after the ignition of the vehicle at a predetermined timing is turned on. Therefore, it is set so that PWM control (hereinafter simply referred to as axis magnetization PWM control) is performed. The excitation signal generator 41 further transmits through the first magnetostrictive film 31 and the second magnetostrictive film 32 when the axis magnetization PWM control for magnetizing the pinion shaft 5 is not performed, that is, during the normal operation of the magnetostrictive torque sensor 30. It is set to perform PWM control (hereinafter simply referred to as torque detection PWM control) for detecting a change in magnetic susceptibility. Here, “temporary” mentioned above means that the axis magnetization PWM control is performed for a predetermined time set in advance in order to sufficiently magnetize the pinion shaft 5 and then the axis magnetization PWM control is stopped. ing. The predetermined time for performing the axis magnetization PWM control may be set as appropriate according to the magnetic characteristics of the pinion shaft 5.

図４は、横軸を時間、縦軸を励磁信号及び励磁電流とした、トルク検出ＰＷＭ制御を行っているときの励磁信号及び励磁電流の変化を示すグラフである。このグラフに示すように、トルク検出ＰＷＭ制御を行っている場合は、スイッチ手段４２のＯＮ時間が短く（例えば、ＤＵＴＹ４％程度）設定され、このとき第１検出コイル３３及び第２検出コイル３４に通電される励磁電流は比較的小さな励磁電流となる。   FIG. 4 is a graph showing changes in the excitation signal and the excitation current when torque detection PWM control is performed with the horizontal axis representing time and the vertical axis representing excitation signal and excitation current. As shown in this graph, when the torque detection PWM control is performed, the ON time of the switch means 42 is set to be short (for example, about DUTY 4%), and at this time, the first detection coil 33 and the second detection coil 34 are set. The energized excitation current is a relatively small excitation current.

一方、図５は、軸磁化ＰＷＭ制御を行っている場合の励磁信号及び励磁電流の変化を示すグラフであり、図４と同様に横軸を時間、縦軸を励磁信号及び励磁電流としている。このグラフに示すように、スイッチ手段のＯＮ時間が長く（例えば、ＤＵＴＹ６０％程度）設定され、これによりピニオン軸５を磁化させるのに十分な比較的大きな励磁電流が第１検出コイル３３および第２検出コイル３４に流れることとなる。ここで、図４，５のグラフに示すように、第１検出コイル３３及び第２検出コイル３４に流れる励磁電流は、励磁信号がＯＮ（例えば、５Ｖ）の時に徐々に増加しＯＦＦ（例えば、０Ｖ）の時に徐々に減少する。なお、励磁電流をＰＷＭ方式で制御する場合について説明したが、電流の通電量の制御が可能であればこの方式に限られるものではない。   On the other hand, FIG. 5 is a graph showing changes in the excitation signal and the excitation current when the axis magnetization PWM control is performed. As in FIG. 4, the horizontal axis represents time, and the vertical axis represents the excitation signal and excitation current. As shown in this graph, the ON time of the switch means is set to be long (for example, about DUTY 60%), whereby a relatively large excitation current sufficient to magnetize the pinion shaft 5 is generated by the first detection coil 33 and the second detection coil 33. It will flow to the detection coil 34. Here, as shown in the graphs of FIGS. 4 and 5, the excitation current flowing through the first detection coil 33 and the second detection coil 34 gradually increases when the excitation signal is ON (for example, 5 V) and is OFF (for example, 0V), it gradually decreases. Although the case where the excitation current is controlled by the PWM method has been described, the present invention is not limited to this method as long as the current supply amount can be controlled.

図３に示すように、電子制御装置５０は、検出回路３５から出力されたトルク検出信号ＶＴ３を読み込むトルク信号読込部５１と、このトルク信号読込部５１で読み込まれたトルク検出信号に基づいて補助操舵トルクを求める補助操舵力決定部５３とを備え、この補助操舵力決定部５３によって求められた補助操舵トルクに基づいて電動機１１を駆動制御する。さらに、電子制御装置５０は、検出回路３５から出力された電圧信号ＶＴ１，ＶＴ２に基づいて故障検出信号ＶＴＦを求める故障検出信号算出部５２と、この故障検出信号ＶＴＦが予め設定された所定の範囲を外れた場合に磁歪式トルクセンサの故障検出を行う故障検出部５４とを備えている。ここで、故障検出信号ＶＴＦは（１）式により求めることができる。なお、（１）式においてＣは定数である。
ＶＴＦ＝ＶＴ１＋ＶＴ２＋Ｃ ・・・（１） As shown in FIG. 3, the electronic control unit 50 assists based on the torque signal reading unit 51 that reads the torque detection signal VT <b> 3 output from the detection circuit 35 and the torque detection signal read by the torque signal reading unit 51. An auxiliary steering force determination unit 53 for obtaining a steering torque is provided, and the electric motor 11 is driven and controlled based on the auxiliary steering torque obtained by the auxiliary steering force determination unit 53. Furthermore, the electronic control unit 50 includes a failure detection signal calculation unit 52 that obtains a failure detection signal VTF based on the voltage signals VT1 and VT2 output from the detection circuit 35, and a predetermined range in which the failure detection signal VTF is set in advance. And a failure detection unit 54 for detecting a failure of the magnetostrictive torque sensor when it is off. Here, the failure detection signal VTF can be obtained by equation (1). In the equation (1), C is a constant.
VTF = VT1 + VT2 + C (1)

電子制御装置５０は、故障検出部５４によって、故障検出信号ＶＴＦが所定の範囲から外れたと判定された場合、補助操舵力決定部５３の出力を遮断する遮断手段５５を作動させて、実質的にピニオン軸５に作用するトルクの検出を行わないように制御を行うとともに、故障が検出された旨を故障検出表示等によって報知する。   When the failure detection unit 54 determines that the failure detection signal VTF is out of the predetermined range, the electronic control unit 50 operates the blocking means 55 that blocks the output of the auxiliary steering force determination unit 53 to substantially Control is performed so that the torque acting on the pinion shaft 5 is not detected, and the fact that a failure has been detected is notified by a failure detection display or the like.

また、電子制御装置５０は、上述した励磁信号発生部４１によって軸磁化ＰＷＭ制御が行われている場合、補助操舵力決定部５３の出力を遮断するとともに、故障検出部５４による故障検出を停止させる。つまり、電子制御装置５０は、実質的に、故障検出部５４による故障検出を禁止するとともに、電圧信号ＶＴ１，ＶＴ２に基づいたトルク検出信号ＶＴ３に基づいたトルク検出を禁止して、補助操舵力を発生させるための電動機１１の制御を行わないようにする。   Further, the electronic control unit 50 shuts off the output of the auxiliary steering force determination unit 53 and stops the failure detection by the failure detection unit 54 when the shaft magnetization PWM control is performed by the excitation signal generation unit 41 described above. . That is, the electronic control device 50 substantially prohibits the failure detection by the failure detection unit 54 and prohibits the torque detection based on the torque detection signal VT3 based on the voltage signals VT1 and VT2, thereby increasing the auxiliary steering force. The control of the electric motor 11 for generation is not performed.

すなわち、電子制御装置５０は、例えば、車両のイグニッションが乗員によりＯＮ操作され磁歪式トルクセンサ３０が起動すると、励磁信号発生部４１によって、一時的、具体的にはピニオン軸５が十分に磁化される所定の時間だけ軸磁化ＰＷＭ制御を行うべくスイッチ手段４２のＯＮ／ＯＦＦ制御を行う。すると、第１検出コイル３３及び第２検出コイル３４の両者にはそれぞれ同等の励磁電流が流れてバイアス磁界が発生しピニオン軸５が磁化されることとなる。そして、電子制御装置５０は、この軸磁化ＰＷＭ制御を行っている時に、故障検出部５４による故障検出の制御と、電圧信号ＶＴ３に基づいたトルク検出の制御とを禁止状態に切換える。   That is, for example, when the ignition of the vehicle is turned ON by the occupant and the magnetostrictive torque sensor 30 is activated, the electronic control device 50 temporarily, specifically, the pinion shaft 5 is sufficiently magnetized by the excitation signal generator 41. ON / OFF control of the switch means 42 is performed so as to perform the axial magnetization PWM control for a predetermined time. Then, an equivalent exciting current flows through both the first detection coil 33 and the second detection coil 34, a bias magnetic field is generated, and the pinion shaft 5 is magnetized. Then, the electronic control unit 50 switches the failure detection control by the failure detection unit 54 and the torque detection control based on the voltage signal VT3 to the prohibited state while performing the axial magnetization PWM control.

そして、軸磁化ＰＷＭ制御を開始してから上述の所定の時間が経過した後、軸磁化ＰＷＭ制御を停止して、次いでトルク検出ＰＷＭ制御を開始するとともに電子制御装置５０により禁止していた故障検出部５４による故障検出および電圧信号ＶＴ３に基づいたトルク検出を許可状態に切換えて、それぞれ故障検出の制御及びトルク検出の制御を開始する。   Then, after the predetermined time has elapsed since the start of the shaft magnetization PWM control, the shaft magnetization PWM control is stopped, and then the torque detection PWM control is started and the failure detection that is prohibited by the electronic control unit 50 is detected. The failure detection by the unit 54 and the torque detection based on the voltage signal VT3 are switched to the permitted state, and the failure detection control and the torque detection control are started.

したがって、上述した実施の形態によれば、所定のタイミングで励磁信号発生部４１、スイッチ手段４２よって軸磁化ＰＷＭ制御を行って一時的に第１検出コイル３３及び第２検出コイル３４でバイアス磁界を発生させてピニオン軸５をバイアス磁化させることで、バイアス磁界を停止した後も、強磁性のピニオン軸５に磁化が残留してバイアス磁化として作用させることができるため、外部磁気タフネスの向上を図りつつ、従来のように常時電流を検出コイルに通電している場合と比較して、通電を一時的に行う分だけ消費電流を低減することができるとともに、例えばトルク検出や故障検出などへの影響も低減して信頼性を向上することができる。   Therefore, according to the above-described embodiment, the excitation signal generator 41 and the switch means 42 perform the axial magnetization PWM control at a predetermined timing, and the first detection coil 33 and the second detection coil 34 temporarily generate the bias magnetic field. By generating and biasing the pinion shaft 5, the magnetization remains in the ferromagnetic pinion shaft 5 even after the bias magnetic field is stopped, so that it can act as bias magnetization, so that the external magnetic toughness is improved. However, compared to the conventional case where current is always supplied to the detection coil, the current consumption can be reduced by the amount of current that is temporarily supplied and, for example, the effect on torque detection, failure detection, etc. And reliability can be improved.

また、消費電流が低減されることで回路の発熱を抑制できるため、耐熱性の比較的低い部品を使用することが可能になり、したがって、部品のコスト低減を図ることができる。
さらに、磁歪式トルクセンサを起動する時にバイアス磁界を一時的に発生させることで、ピニオン軸５を磁化させるためのバイアス磁界によるトルク検出への影響を抑制することができるため、外部磁界タフネスを向上しつつ更なるトルク検出の信頼性を向上できる。 In addition, since the heat generation of the circuit can be suppressed by reducing the current consumption, it is possible to use a component having relatively low heat resistance, and therefore it is possible to reduce the cost of the component.
Further, by temporarily generating a bias magnetic field when starting the magnetostrictive torque sensor, the influence of the bias magnetic field for magnetizing the pinion shaft 5 on the torque detection can be suppressed, so that the external magnetic field toughness is improved. However, the reliability of further torque detection can be improved.

そして、故障検出部５４によって故障検出を行っているときにはピニオン軸５を磁化させるためのバイアス磁界が発生していないため、このバイアス磁界が故障検出へ影響を及ぼすのを防止することができ、その結果、外部磁界タフネスを向上しつつ故障検出部５４による故障検出の信頼性も向上できる。   When a failure is detected by the failure detection unit 54, no bias magnetic field for magnetizing the pinion shaft 5 is generated, so that this bias magnetic field can be prevented from affecting the failure detection. As a result, the reliability of failure detection by the failure detector 54 can be improved while improving the external magnetic field toughness.

さらに、操舵トルクを検出するための磁歪式トルクセンサ３０の外部磁界タフネスを向上しつつ消費電流を低減することができるため、この磁歪式トルクセンサ３０を備える車両用の電動パワーステアリング装置の消費電流低減及び信頼性の向上に寄与することができる。   Further, since the current consumption can be reduced while improving the external magnetic field toughness of the magnetostrictive torque sensor 30 for detecting the steering torque, the current consumption of the electric power steering device for a vehicle including the magnetostrictive torque sensor 30 is reduced. It can contribute to reduction and improvement of reliability.

なお、この発明は上述した実施の形態に限られるものではなく、例えば、電動パワーステアリング装置のピニオン軸５に作用するトルク以外に、強磁性を示す回転軸やシャフト等に作用するトルクを検出する磁歪式トルクセンサに適用することができる。
また、上記実施の形態では所定のタイミングとしてイグニッションがＯＮ操作された磁歪式トルクセンサ３０の起動時に、一時的に、具体的にはピニオン軸５が十分に磁化される所定の時間だけ軸磁化ＰＷＭ制御を行う場合について説明したが、これに限られるものではなく、例えば、車両が停車している時など、乗員によるステアリング操作がなされる虞のないタイミングであればよい。 The present invention is not limited to the above-described embodiment. For example, in addition to the torque acting on the pinion shaft 5 of the electric power steering device, the torque acting on the rotating shaft, shaft, etc. exhibiting ferromagnetism is detected. It can be applied to a magnetostrictive torque sensor.
Further, in the above embodiment, when the magnetostrictive torque sensor 30 whose ignition is turned on as a predetermined timing is started, the axis magnetization PWM is temporarily, specifically, a predetermined time during which the pinion shaft 5 is sufficiently magnetized. Although the case where the control is performed has been described, the present invention is not limited to this, and any timing may be used as long as there is no possibility that the steering operation by the occupant is performed, for example, when the vehicle is stopped.

〔他の実施形態〕
この発明は、前述した実施形態の電動パワーステアリング装置への適用に限るものではなく、ステアリング・バイ・ワイヤ・システムの車両用ステアリング装置にも適用可能である。ステアリング・バイ・ワイヤ・システムとは、操舵手段と転舵機構とが機械的に分離されていて、操舵手段に作用する操舵トルクに応じて、転舵機構に設けられたステアリングモータを駆動して車両の転舵輪を転舵させる操舵システムであり、この操舵手段に作用する操舵トルクの検出にこの発明に係る磁歪式トルクセンサを用いることができる。 [Other Embodiments]
The present invention is not limited to application to the electric power steering apparatus of the above-described embodiment, but can also be applied to a vehicle steering apparatus of a steering-by-wire system. In the steering-by-wire system, the steering means and the steering mechanism are mechanically separated, and the steering motor provided in the steering mechanism is driven according to the steering torque acting on the steering means. This is a steering system for turning steered wheels of a vehicle, and the magnetostrictive torque sensor according to the present invention can be used for detection of steering torque acting on the steering means.

本発明の実施の形態における磁歪式トルクセンサを備えた車両用電動パワーステアリング装置の概略構成図である。1 is a schematic configuration diagram of a vehicular electric power steering apparatus including a magnetostrictive torque sensor according to an embodiment of the present invention. 本発明の実施の形態における磁歪式トルクセンサの概略構成図である。It is a schematic block diagram of the magnetostrictive torque sensor in embodiment of this invention. 本発明の実施の形態における電子制御装置の概略構成を示すブロック図である。It is a block diagram which shows schematic structure of the electronic controller in embodiment of this invention. 本発明の実施の形態における通常動作時の励磁信号と励磁電流との変化を示すグラフである。It is a graph which shows the change of the excitation signal at the time of normal operation in embodiment of this invention, and an excitation current. 本発明の実施の形態におけるバイアス磁化時の励磁信号と励磁電流と変化を示すグラフである。It is a graph which shows the excitation signal at the time of bias magnetization in embodiment of this invention, an excitation current, and a change. 従来の磁歪式トルクセンサの概略構成図である。It is a schematic block diagram of the conventional magnetostrictive torque sensor. 従来の磁歪式トルクセンサにおける外部磁気タフネスを向上する回路の一例を示す概略構成図である。It is a schematic block diagram which shows an example of the circuit which improves the external magnetic toughness in the conventional magnetostrictive torque sensor.

符号の説明Explanation of symbols

５ ピニオン軸（シャフト）
３１ 第１磁歪膜（磁歪膜）
３２ 第２磁歪膜（磁歪膜）
４１ 励磁信号発生部（バイアス磁化手段）
４２ スイッチ手段（バイアス磁化手段）
３３ 第１検出コイル（検出手段、バイアス磁化手段）
３４ 第２検出コイル（検出手段、バイアス磁化手段）
５４ 故障検出部（故障検出手段） 5 Pinion shaft (shaft)
31 First magnetostrictive film (magnetostrictive film)
32 Second magnetostrictive film (magnetostrictive film)
41 Excitation signal generator (bias magnetization means)
42 Switch means (bias magnetization means)
33 First detection coil (detection means, bias magnetization means)
34 Second detection coil (detection means, bias magnetization means)
54 Failure detection unit (failure detection means)

Claims (7)

強磁性のシャフトに設けられた磁歪膜と、
該磁歪膜の磁気特性の変化を検出し、該検出結果に基づいて前記シャフトに入力されるトルクを検出するトルク検出手段と、
前記シャフトにバイアス磁界を印加して磁化させるバイアス磁化手段とを備え、
該バイアス磁化手段が所定のタイミングで一時的にシャフトを十分に磁化させるために予め設定された所定時間だけバイアス磁界を発生させる磁歪式トルクセンサであって、
前記バイアス磁化手段は、前記シャフトに対向して設けられたコイルに電流を流すことによりバイアス磁界を発生させることを特徴とする磁歪式トルクセンサ。 A magnetostrictive film provided on a ferromagnetic shaft;
Torque detection means for detecting a change in magnetic characteristics of the magnetostrictive film and detecting torque input to the shaft based on the detection result;
Bias magnetization means for applying a bias magnetic field to the shaft and magnetizing the shaft,
The bias magnetization means a magnetostrictive torque sensor that generates only the bias magnetic field a preset time to fully magnetized temporarily shaft at a predetermined timing,
The magnetostrictive torque sensor according to claim 1, wherein the bias magnetizing unit generates a bias magnetic field by causing a current to flow through a coil provided to face the shaft. 前記バイアス磁化手段は、起動時に一時的にバイアス磁界を発生させることを特徴とする請求項１に記載の磁歪式トルクセンサ。   The magnetostrictive torque sensor according to claim 1, wherein the bias magnetizing unit temporarily generates a bias magnetic field at startup. 前記検出手段の検出結果に基づいて故障検出を行う故障検出手段を備え、前記バイアス磁化手段が所定のタイミングで一時的にバイアス磁界を発生させている間は、トルクの検出及び故障検出を禁止することを特徴とする請求項１又は２に記載の磁歪式トルクセンサ。   A failure detection unit that detects a failure based on the detection result of the detection unit is provided, and torque detection and failure detection are prohibited while the bias magnetization unit temporarily generates a bias magnetic field at a predetermined timing. The magnetostrictive torque sensor according to claim 1, wherein the magnetostrictive torque sensor is provided. 前記トルク検出手段は、前記磁歪膜の磁気特性の変化を検出するために前記シャフトに対向して設けられた検出コイルに電流を流すことによりトルクを検出し、
前記バイアス磁化手段は、前記トルク検出手段がトルク検出時に前記検出コイルに電流を通電する時間よりも長い時間前記検出コイルに電流を流すことによりバイアス磁界を発生させることを特徴とする請求項１に記載の磁歪式トルクセンサ。 The torque detection means detects torque by passing a current through a detection coil provided facing the shaft in order to detect a change in magnetic characteristics of the magnetostrictive film ,
The bias magnetizing unit generates a bias magnetic field by causing a current to flow through the detection coil for a time longer than a time during which the torque detection unit energizes the detection coil when the torque is detected. The magnetostrictive torque sensor described. 前記トルク検出手段は、前記バイアス磁化手段によって一時的にバイアス磁界を発生させている間は、トルクの検出を禁止することを特徴とする請求項１に記載の磁歪式トルクセンサ。   2. The magnetostrictive torque sensor according to claim 1, wherein the torque detection unit prohibits detection of torque while the bias magnetization unit temporarily generates a bias magnetic field. 3. 前記トルク検出手段は、前記磁歪膜の磁気特性の変化を検出するために前記シャフトに対向して設けられた検出コイルに電流をＰＷＭ制御にて通電することによりトルクを検出し、
前記バイアス磁化手段は、前記シャフトにバイアス磁界を印加するために前記検出コイルに流す電流をＰＷＭ制御にて行い、前記バイアス磁化手段のＰＷＭ制御のＯＮ時間が前記トルク検出手段のＰＷＭ制御のＯＮ時間よりも長いことを特徴とする請求項１に記載の磁歪式トルクセンサ。 The torque detecting means detects torque by energizing a current by PWM control to a detection coil provided facing the shaft in order to detect a change in magnetic characteristics of the magnetostrictive film,
It said bias magnetic means, the current flowing in the detection coil in order to apply a bias magnetic field to the shaft have rows in the PWM control, ON the PWM control of the ON time of the PWM control of the bias magnetization means the torque detecting means The magnetostrictive torque sensor according to claim 1, wherein the magnetostrictive torque sensor is longer than time . 操舵トルクを磁歪式トルクセンサによって検出し、検出した操舵トルクに応じて電動機を駆動して車両を転舵させる電動ステアリング装置において、前記磁歪式トルクセンサは、請求項１乃至６の何れか一項に記載の磁歪式トルクセンサであることを特徴とする電動ステアリング装置。   7. The electric steering device for detecting steering torque by a magnetostrictive torque sensor and driving the electric motor according to the detected steering torque to steer the vehicle, wherein the magnetostrictive torque sensor is any one of claims 1 to 6. An electric steering device comprising the magnetostrictive torque sensor according to claim 1.
JP2007308817A 2007-11-29 2007-11-29 Magnetostrictive torque sensor and electric steering device Expired - Fee Related JP4572227B2 (en)

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US20090314573A1 (en) 2009-12-24

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